PROJECT SUMMARY/ABSTRACT People experiencing chronic homelessness comprise a small yet high-morbidity, high-cost subset of the larger homeless population and are disproportionately impacted by alcohol-related harm. Unfortunately, traditional abstinence-based treatment does not adequately reach or engage this population, and both firsthand (problems stemming from one?s own alcohol use) and secondhand (problems stemming from others? alcohol use) alcohol-related harm persists even after housing attainment. There have therefore been calls for more flexible and client-centered approaches tailored to this population?s needs. Housing First, which entails the provision of immediate, permanent, low-barrier, nonabstinence-based housing, is a response to this call. Research has shown that Housing First is associated with decreased alcohol use, alcohol-related harm, and publicly funded service utilization. Nonetheless, Housing First residents continue to experience both first- and secondhand alcohol-related harm. Thus, further community-based interventions are necessary. To this end, a pilot project was conducted in which researchers as well as Housing First residents, staff and management codeveloped, implemented, and initially evaluated the Life Enhancing Alcohol-management Program (LEAP). The LEAP entails low-barrier, community-level, house-wide resident programming?including leadership opportunities, activities, and pathways to recovery. At the 6-month follow up, LEAP participants reported significantly more engagement in meaningful activities than control participants (p < .001). Moreover, high levels of LEAP program engagement (>2 activities per month) predicted significant reductions in alcohol use and alcohol-related harm (ps < .01). To build on these promising findings, we propose a larger, cluster- randomized controlled trial of LEAP (N=500) as an innovative, community-based, and client-driven adjunct to Housing First. In the proposed project, 10 Housing First sites will be optimally matched and block randomized on a rolling basis to either LEAP or services-as-usual control conditions. At LEAP sites, research staff will work with housing staff and residents to conduct a needs assessment, form a community advisory board, and develop and implement this community-level intervention. Participants in the LEAP evaluation will meet criteria for at-risk drinking and will be assessed at baseline, 3-, 6-, and 12-month follow-ups. Analyses will test LEAP effectiveness in increasing engagement in meaningful activities, decreasing alcohol use, ameliorating both first- and secondhand alcohol-related harm, and improving quality of life. Engagement in meaningful activities will also be tested as a mediator of the LEAP effect on alcohol and quality-of-life outcomes. Finally, we will assess whether LEAP is associated with reduced costs stemming from participants? use of emergency health-care and criminal justice services.